Japanese Patent Application Laid-open Publication No. 179191/1999 (Application No. 357263/1997) discloses a technology for increasing reaction efficiency in a plurality of reaction pipes. In this technology, a regenerative combustion apparatus of a high temperature air combustion type is used in elevating a temperature inside a furnace in which series of reaction pipes are laterally arranged.
Japanese Patent Application Laid-open Publication No. 152166/2001 (Application No. 343624/1999) discloses a technology relating to a reaction furnace which employs high temperature air combustion technology. “High Temperature Air Combustion Technology” is defined as a technology which carries out combustion by pre-heating combustion air to as high as 800° C., feeding the high temperature combustion air to a combustion chamber at a high speed, and injecting a fuel into the combustion air. This disclosed technology is capable of reducing as much as possible a difference in temperature among fields of temperature inside a furnace in which series of reaction pipes are arranged, without enlarging a combustion chamber.
Employing the high temperature air combustion technology can reduce a difference in temperature inside the reaction furnace as much as possible. In a configuration, however, there are many reaction pipes or series of reaction pipes, existence of the pipes becomes resistance against thermal conduction. Consequently, the temperature of a space defined among the reaction pipes and the temperature of the outside of such space tend to differ more largely. Such a difference in temperature, in turn, will cause cracks of the pipes or coking. For this reason, it is necessary to reduce such a difference in temperature. Thermal conduction to the pipes depends upon radiant heat from a furnace wall. The pipes located outer cast shadows or become obstacles for inner pipes in thermal conduction. The respective pipes are not uniformly heated, thereby causing a problem that an amount of heat received by the entire pipes, namely efficiency in thermal conduction is decreased.
It is therefore an object of the present invention to provide a method for controlling combustion of a reaction furnace employing high temperature air combustion technology and a reaction furnace employing the same technology which is capable of reducing a difference in temperature inside the furnace without causing cracks of the pipes or coking in the pipes.
It is another object to provide a reaction furnace and a method for controlling combustion of a reaction furnace that are capable of preventing significant ununiformity in temperature distribution on a pipe wall in a circumferential direction of each reaction pipe.
It is further another object to provide a reaction furnace and a method for controlling combustion of a reaction furnace that are capable of suppressing an increase in CO (carbon oxide) concentrations without lowering thermal efficiency.
It is yet another object to provide a reaction furnace and a method for controlling combustion of a reaction furnace that are capable of increasing an amount of received heat (efficiency in thermal conduction) more than ever.